1. Field of the Invention
The present invention relates to a radiation image processing apparatus, a radiation image processing method, a program, and a computer-readable medium for producing computed tomography (CT) images by CT reconstruction based on a plurality of projection images taken by using a two-dimensional sensor. In particular, the present invention relates to a radiation image processing apparatus, a radiation image processing method, a program, and a computer-readable medium in which the need to repeat a radiograph is determined by detecting a movement of a subject to be inspected based on the projection images.
2. Description of the Related Art
In CT radiography, it is known that, if a subject to be inspected moves during CT scanning, appropriate CT images for CT reconstruction usually cannot be achieved. To solve this problem, CT radiographic devices generally have a function that provides a preview of a CT image after the CT scanning to determine the need to repeat a radiograph based on the quality of the displayed CT image.
The determination is made by, for example, the operator's eye, a CT scan device that automatically determines based on the CT image quality, or both. In addition, an operator may determine the adequacy of the preset parameters based on the quality of the CT preview image. If the operator determines that the parameters are inadequate, the operator re-radiographs the subject after adjusting the parameters, as is disclosed in Japanese Patent Laid-Open No. 2002-365239.
However, in the methods in which the need to repeat a radiograph is determined based on the CT image created by CT reconstruction, the time required for the CT reconstruction delays the determination of the need to repeat a radiograph, and therefore, degrades the throughput of the CT inspection.
Additionally, the method in which an operator determines the need to repeat a radiograph by eye has drawbacks in that the criterion for the determination is not clear and the operator must make a complicated decision. These drawbacks also degrade the throughput of the CT inspection.